CFGBlock* add_block(int ip, bool loop=false) {
CFGBlock* blk = find_block(ip);
if(blk) return blk;
blk = new CFGBlock(ip, loop);
// Inherit the current exception handler
blk->set_exception_handler(current_->exception_handler());
set_block(ip, blk);
return blk;
}
void build() {
find_backward_gotos();
// Construct the root block specially.
if(blocks_[0]) {
root_ = blocks_[0];
} else {
root_ = new CFGBlock(0);
blocks_[0] = root_;
}
current_ = root_;
VMMethod::Iterator iter(stream_, stream_size_);
for(;;) {
if(CFGBlock* next_block = find_block(iter.position())) {
if(next_block->loop_p()) {
// The handler wasn't setup originally, so we have to set it now.
next_block->set_exception_handler(current_->exception_handler());
close_current(iter, next_block);
} else {
current_ = next_block;
}
}
switch(iter.op()) {
case InstructionSequence::insn_goto:
case InstructionSequence::insn_goto_if_true:
case InstructionSequence::insn_goto_if_false:
if(iter.operand1() > iter.position()) {
current_->add_child(add_block(iter.operand1()));
start_new_block(iter);
} else {
#ifndef NDEBUG
CFGBlock* loop_header = find_block(iter.operand1());
assert(loop_header);
assert(loop_header->exception_handler() == current_->exception_handler());
#endif
}
break;
case InstructionSequence::insn_setup_unwind: {
assert(iter.operand1() > iter.position());
CFGBlock* handler = add_block(iter.operand1());
handler->set_exception_type(iter.operand2());
current_->add_child(handler);
CFGBlock* body = start_new_block(iter);
assert(body); // make sure it's not at the end.
body->set_exception_handler(handler);
break;
}
case InstructionSequence::insn_pop_unwind: {
assert(current_->exception_handler());
CFGBlock* cont = start_new_block(iter);
CFGBlock* current_handler = cont->exception_handler();
assert(current_handler);
// Effectively pop the current handler by setting the
// blocks handler (and thus all blocks after it) to the current
// handlers handler.
cont->set_exception_handler(current_handler->exception_handler());
break;
}
case InstructionSequence::insn_ensure_return:
case InstructionSequence::insn_raise_exc:
case InstructionSequence::insn_raise_return:
case InstructionSequence::insn_raise_break:
case InstructionSequence::insn_reraise:
case InstructionSequence::insn_ret:
start_new_block(iter);
break;
}
if(!iter.advance()) break;
}
current_->set_end_ip(iter.position());
}